Both closed clamps made from tubular stock as well as open clamps provided with mechanical interconnecting means, which utilized plastically deformable so-called "Oetiker" ears have proved immensely successful over more than three decades. My prior U.S. Pat. Nos. 2,614,304; 2,847,742; 3,082,498 and 3,402,436 are representative of some of the types of clamps which have been sold worldwide in large quantities. With the advent of new plastic, relatively harder hose materials, as used, for example, with axle boots, the need for an internal clamping surface devoid of any gaps, discontinuities or steps became imperative to assure complete tightening of the axle boot. Additionally, the mechanical connection used heretofore with open clamps and consisting of one or more substantially U-shaped members bent out of the material about an axis transverse to the longitudinal direction of the clamping band, as disclosed, for instance, in my prior U.S. Pat. No. 3,475,793, imposed limitations on the strength to resist opening forces, i.e., of holding together the overlapping band ends of open clamps, particularly when higher tightening forces are used. My prior U.S. Pat. No. 4,299,012; 4,315,348 and 4,622,720 disclose solutions which have also proved immensely successful in practice. Furthermore, the relatively narrow canoe-shaped reinforcing groove as proposed in my prior U.S. Pat. No. 3,475,793 has been vastly improved in the bridging portion of a so-called "Oetiker" ear by a relatively shallow depression of approximately rectangular configuration in plan view with the sides thereof extending at least over half the length and width of the bridging portion. The details of the improved reinforcing depression are disclosed in my copending application Ser. No. 06/622,764, the details of which are incorporated herein by reference. It is noted that the corresponding British application has issued as British Patent 2,160,577.
One of the reasons for the immense commercial success of my various clamp products is attributable to the particular features obtainable with the plastically deformable, so-called "Oetiker" ear which, when plastically deformed to tighten the clamp about the object to be fastened thereby, provides an automatic spring action to compensate for changes in temperature and/or pressure. This compensating action, however, is limited by the yield strength of the clamping band material of which the plastically deformable ear is also made. Once the elastic limit of the clamping band material is reached, the automatic spring action of the plastically deformed so-called "Oetiker" ear is jeopardized. In other words, the maximum spring path allowed by an "Oetiker" ear, i.e., the maximum increase in the circumferential dimension of the clamp, is limited by the elastic limit of the clamping band material. If this elastic limit is exceeded, for example, as a result of temperature increases in the cooling medium carried by a radiator hose, there exists a serious leakage problem when the cooling medium cools down again because the clamp will not elastically return to its original dimensions with the same clamping force.
These problems have been confronted by clamp structures in which the plastically deformed "Oetiker" ear was formed in a separate connecting member which could be made of a material having greater yield strength than the material of the clamping band. My prior U.S. Pat. No. 2,847,742 is representative of this approach. However, both from a cost point of view as well as from an installation point of view, it is desirable to make the plastically deformable ear integral with the clamping band.
My prior U.S. Pat. No. 3,475,793 proposed the use of tensional spring elements formed in the clamping band itself which was then made from appropriate spring steel material as contrasted to soft steel. If in addition to one or more tensional spring elements, also a plastically deformable "Oetiker" ear was desired in such open clamp, it became necessary to submit the clamping band to additional heat treatment in order to provide a plastically deformable material within the area of the "Oetiker" ear.
As hermetically sealed cooling systems in the automotive industry permit ever-increasing temperatures of the cooling fluid and as the new hose materials exhibit greater likelihood to change the external configuration within the area of the clamping band where grooves or indentations are formed, there exists a need for increasing the maximum spring path, i.e., provide greater elastic automatic compensation to maintain tightness of the hose connection.
The European Patent 0 280 598 already addressed this problem to establish an "elasticity reserve" by the use of a loop formed in the clamping band which is externally surrounded by a spring sleeve. To cover the gap underneath the loop and to limit the elastic deflection of the loop and its external cylindrical spring sleeve, a separate part is used which is installed so as to extend underneath the clamping band and over the spring sleeve. This arrangement requires a number of parts which increases the cost of manufacture and assembly and additionally requires a separate part to cover the gap underneath the loop. Furthermore, steps are formed at the point of mechanical connection between the inner and outer band portions.